1. Field of the Invention
Embodiments of the invention relate to the field of valves used to control the flow of process media. More particularly, the present invention relates to an apparatus for providing lubricant to a secondary seal of a process valve in situ without the need for disassembly and re-assembly.
2. Discussion of Related Art
Gate valves or knife gate valves are disposed within a pipeline to control the flow of process media. Knife gate valves are particularly adapted for abrasive slurries, but may be used for any fluid process control. These types of valves get their name from the vertical movement of a gate between open and closed position. Movement of the gate is controlled by an actuator which may be manually driven or may be automated. The gate slides between a pair of opposed sealing sleeves disposed within a housing which is attached to the process pipeline through the use of flanges and mounting fasteners. During valve operation, the sealing sleeves move axially coming together when the gate is lifted to an open position and separating when the gate drops into a closed position.
A secondary seal, in addition to the primary seals, may also be employed to engage the gate during the valve cycle. The secondary seal acts to prevent process media which may seep through the primary sleeves from leaking around the gate or toward the actuator end of the valve. To promote cohesive sliding of the gate during operation, lubricating fluid has been applied to grooves within the secondary seal and applied to the gate as the gate traverses through the secondary seal. Gate lubrication provides smoother gate action and longer seal life as well as reducing the amount of force necessary to actuate the gate. However, once this lubricant is depleted, the secondary seals had to be removed from the valve in order to provide additional lubricant. In particular, the valve was disassembled, the secondary seals were removed, lubricant was added, the secondary seals were re-installed and the valve was reassembled with the added lubricant in the secondary seals. This required process line down-time which negatively impacted manufacturing processes.